Keyed system for connection of filter cartridge to filter holder

ABSTRACT

Embodiments of a key system for filters and their connecting heads/holders are shown. The filter cartridge and its holder each have a keyed surface, one being a protruding “key” and one being a recessed “lock”. Cooperation of these keyed surfaces is required in order for the filter cartridge to be installed in the holder, so that mismatched cartridges cannot be installed into the holder, for example, to prevent a particular type of cartridge from being placed in a filtration or other process where it would be inappropriate, or undesired. The keyed surfaces are selectively locate-able preferably at different circumferential locations on a perimeter of the filter and a corresponding location on a perimeter of the head/holder. The perimeter may be, for example, on an outer shoulder surface of a filter and an inner surface of a valve head, or on outer and inner surfaces of connectors that provide a liquid seal between the filter and the head/holder.

BACKGROUND OF THE INVENTION

This application is a continuation of patent application Ser. No.09/928,666, filed Aug. 11, 2001, and issued Feb. 24, 2004 as U.S. Pat.No. 6,695,891, which is a non-provisional application claiming priorityof provisional patent application Ser. No. 60/224,632, filed Aug. 11,2000, and also claims priority of prior, provisional patent applicationSer. No. 60/272,221, filed Feb. 27, 2001, which are herein incorporatedby this reference.

FIELD OF THE INVENTION

This invention relates generally to fluid filters and filter cartridgesand connections for the filters/cartridges to piping, valving, brackets,and other holders that cooperate with the filters/cartridges to makethem operative in a flowing fluid system. More specifically, thisinvention relates to a system for “keying” a particular filter cartridgeor filter to a particular cooperating filter head member or filter valvehead.

SUMMARY OF THE INVENTION

The invention is an apparatus and method wherein a portion of a fluidcartridge-holder connection is structurally adapted so that only matchedfilter cartridges and holders can cooperate to allow installation of thefilter cartridge in the holder and/or to form a fluid seal. In otherwords, each filter cartridge and holder combination or “set” is “keyed”so that only that particular filter cartridge design mates with thatholder. According to the invention, there are created variouscartridge-holder sets that each have the adaptation, but the adaptationis slightly offset for each set compared to the other sets. This way, afilter cartridge from one set may not be mixed with a cartridge fromanother set, and, therefore, a filter cartridge may not be installed onany but its own matching holder.

The adaptation preferably involves a varying location of a “key”protrusion and a “lock” recess combination, such as a tab-slotcombination, typically with mating protrusion(s) and recess(es) being ata certain angle on a circumference for one cartridge-holder set and amating protrusion(s) and recess(s) of a similar or identical shape beingat a different angle on the circumference for another cartridge-holderset, and so on, for eachsimilarly-shaped-but-differently-located-adaptation cartridge and holderset. In other words, the key protrusion and the lock recess areselectably locateable around cooperating perimeters of a filtercartridge and its holder. The key and lock structures (hereaftertypically called “key protrusion” or “protrusion” and “lock recess” or“recess”, respectively) are preferably rigidly molded or otherwisepermanently placed on/in the filter cartridge and holder, and so theyare not considered moveable. They are, however, easily changed in themolding or other manufacturing process, that is, they are easilyselectable by locating them at different angles/locations around acircumferential surface.

This system may include a plurality of sets of filters and holders, eachset having a differently-located key and lock, wherein the key and lockof each set cooperate with each other to allow that filter to beinstalled in that holder, but that filter may not be installed in anyother holder because the key or lock of that filter does not cooperatewith the key or lock of the other holder. The term “key or lock” is usedbecause the key protrusions may be placed on either the filter or theholder, and the lock recess may therefore be placed on the other item.

Thus, for example, a water or beverage filtration facility, experimentalpilot plant, or other filter user may control filter cartridge placementaccurately. A facility with multiple, different filtering applicationsmay have filter cartridges on hand for each of the applications, but thecartridges will not be confused. For example, in a facility in whichthere are two different applications, many of the two different types offilter cartridges may be kept in stock and even may be mixed duringstorage or handling, but the filter cartridges will not be mixed wheninstalled into the filter holders. This is because the filter holder andthe filter cartridges for the first application are “keyed” differentlythan the filter holder and the filter cartridges for the secondapplication. The terms “keying” or “keyed” refer generally to how andwhere the entire key system is located or accomplished, that is, to thepositioning or style of either one or both of the cooperating key andlock structures, rather than specifically to only the location of the“key protrusion.” All the filter cartridges for the first applicationare keyed the same, that is, to match the first application holder, andall the filter cartridges for the second application are keyed the same,to match the second application holder. The keying for the firstapplication and the keying for the second application does not need tobe very different, but may be merely, for example, a slightly differentangular position for the two protrusions and recesses.

Also, a filter manufacturer may control his product lines more carefullyby using the invented key system. A manufacturer may key his holders andfilter cartridges differently for different countries, differentclients, different distributors, or for different time periods. Thistechnique may be used to prevent unauthorized or low-quality copies ofthe manufacturer's filter cartridges from easily being made. With somany differently-keyed cartridges in the marketplace provided by theoriginal manufacturer, the incentive to provide cheap, low qualitycopies will be minimized, due to the expense of retooling for each “keyand lock” set.

The key system may include many different protrusion and recessstructures, for example, tabs and slots (typically thin or elongated barand channel structures or elongated dove-tail structures), bumps andholes (typically rounded or mounded structures with cooperating valleysor holes), wedges and wedge-shaped wells (typically circular sectionstructures); and many other shapes. If a cartridge must be rotated onits longitudinal axis to be installed in a holder, leeway in the recessstructure is supplied so that the protrusion may enter it while thecartridge still has a radial distance to turn. For example, in the caseof an elongated filter that is pushed up into a filter head and thenrotated on its axis to install its top end into a filter head, therecess comprises an axial portion for allowing axial insertion and aradial portion for radial rotation of the filter cartridge relative tothe filter head.

The key system structures are located on surfaces of surfaces of filtercartridges (or “filters”) and holders that contact each other duringconnection of the cartridge to the holder. This may be either surfacesthat are involved in mainly providing a physical connection between thecartridge and holder or that also are involved in providing a fluidconnection between the cartridge and the holder.

An example of key system structure on surfaces that are involved inproviding physical connection, rather than fluid connection, is the keysystem structure on a shoulder of a filter cartridge that fits up into avalve-head holder. These areas are surfaces that do not normallyliquid-seal to each other, but must clear each other if the end of thefilter cartridge is to fit up inside the interior cavity of thevalve-head. The top circumferencial shoulder of the filter cartridge andthe inner surface of a valve-head, typically have areas that come invery close contact, but that are not directly involved in forming aliquid seal between the cartridge and the valve-head. Thesenon-liquid-sealing areas may be keyed so that only a cartridge with acertain keyed surface shape may extend far enough up into the valve-headto be installed and locked into place. For example, tabs or otherprotrusions may be provided on the top surface of a filter spacedoutward from an inlet-outlet neck, but external to the liquid-receivingpassages. These filter cartridge protrusions may mate or “nest” inidentically-located recesses on the inside surface of the valve-headthat receives the cartridge, wherein the valve-head recesses are alsoexternal to the cartridge/valve-head liquid-receiving passages.

The keyed structure on the filter shoulder and the inner surface of thevalve-head holder may be said to be located around the outercircumference of a shoulder of the top end of the filter cartridge andthe cooperating or corresponding inner circumference of the valve-headcavity. Preferably the protruding “key” structure comprises a pluralityof protrusions located within an arc of about 90 degrees or less aroundthe circumference on which it lies, or more preferably within about 70degrees or less. The cooperating recess structure is preferably locatedin the cavity surface, facing the filter cartridge shoulder, and,likewise, the same number of recesses are located within the same amountof circumference, preferably about 90 or less, and, more preferably,about 70 degrees or less. In this type of embodiment, the protruding andrecessed structures do not form a liquid seal(s) between the filtercartridge and the valve-head, because other structure typically nearerthe central axis of the filter cartridge and head serve that purpose.While this preferred key system locates the protrusions on the filtercartridge shoulder and the recesses on the head, the opposite isenvisioned, wherein the protrusions may be inside the filter head andthe recesses may be on the filter cartridge.

Another type of embodiment of the keyed system involves the structurethat create a fluid seal between the filter cartridge and the holder,for example, the inlet and outlet ports of the filter cartridge and therespective, cooperating ports/tubes in the holder that convey liquid toand from the cartridge. In this type of embodiment, the protruding andrecessed structures are located around the inner and outer circumferenceof a tubular connector, comprising a male tube and female receiver, thatallow connection of the filter cartridge and the holder, wherein fluidis conducted through the tubular conductor(s) once the cartridge sealsto the holder. An example of such a tubular connector key systemincludes one in which both the filter holder's inlet and outlet and boththe filter cartridge's inlet and outlet are all tubular and are allkeyed. For example, a filter holder's inlet tube and an outlet tube(that direct flow to a cartridge and from the cartridge, respectively)each have an elongated axial tab that protrudes out from the outercylindrical surface of the inlet tube and outlet tube at a chosencircumferential (also called “radial” or “angular” to imply non-axial)location or locations (that is, at different places on the circumferenceof the tube surfaces). Likewise, the inner cylindrical surfaces of thecartridge's cooperating female tubes (into which the holder inlet tubeand outlet tube slide and seal) have channels or “slots” recessed intothe surfaces at corresponding circumferential positions. This way, theholder inlet and outlet tubes slide into the cartridge ports, with theholder tabs sliding into the cartridge slots without significantresistance. Another cartridge with slots at a different circumferentiallocation, on either one its ports, would not receive the holder tubesand, hence, could not be accidentally or incorrectly installed in thatparticular holder. In such a case, where the filter cartridge has twotubes (inlet and outlet ports), each of the ports could have a differentslot circumferential location, as long as the holder is made to match.For example, the holder's inlet tube tab (and corresponding slot on thecartridge inlet port) could be at “straight up” at 0 degrees, while thetab on the holder's outlet tube (and corresponding slot on the cartridgeoutlet port) could be at 30 degrees offset relative to the inlet tabsand slots. With this type of system, for example, varying additionaldifferent cartridge and holder sets each by an additional 30 degrees,many different sets of keyed cartridges and cooperating holders may bemade. Many other amounts besides 30 degrees could be chosen, but thisamount of offset gives many different combinations while providing anoffset easily seen and judged by a person. The inlet tabs and slots andthe outlet tabs and slots may be varied the independently, for example,many sets may have the inlet tabs and slots at zero (0) degrees, whilethe sets may have differently-positioned outlet tabs and slots. Or, setsmay have inlet tabs and slots that vary from set to set by 10 degrees,while those sets' outlet tabs and slots may vary by 15 degrees, forexample. The mathematics of such a system suggest that practically an“endless” number of sets with different key system structures may bedesigned.

Other key system styles are envisioned, which allow generally flat orsmooth surfaces of the filter cartridge and the holder thatconventionally would contact each other to instead include a key systemstructure that ensures that only a particular type of filter cartridgemay be installed in a particular holder. The key system structure of thevarious sets of filter cartridge and cooperating holders/valve-heads istypically invisible once the filter cartridge is installed. While thismay result in differently-keyed filter cartridges having substantiallysimilarly-shaped outer housings, a manufacturer may include indicia onthe outer surface of the filter cartridge to indicate the differentmedia or other filter differences. Also, a user may look at the keysystem structure as long as the filter cartridge is uninstalled. In anyevent, when the user attempts to install a cartridge, onlyproperly-keyed cartridges can be installed into theholder/valve-head/manifold.

By “holder” is meant any of a variety of devices that receive and sealto a replaceable filter or filter cartridge. This can include a valvehead (including valving to shut off piping when the cartridge isremoved), a filter bracket that supports the cartridge and providesfluid flow conduits into and out of the cartridge, and other devicesthat contact and are in fluid communication with the cartridge.

By “filter” or “filter cartridge” is meant any container of filtrationor treatment media that is connected to a holder for fluid communicationwith the holder to filter and/or treat the fluid brought into it via theholder. The keyed system invention may be applied to whatever structureof a filtering unit is inserted into the head or other holder, whichmight be a unitary filter or a filter cartridge encased partially in anouter housing below the level where the filter cartridge engages in thehead.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a bottom perspective view of one embodiment of a filter headaccording to the invention, illustrating one embodiment of recesses forthe invented key system.

FIG. 2 is a top perspective view of one embodiment of a filter cartridgeaccording to the invention, illustrating an embodiment of protrusionsfor the invented key system cooperating with the recesses of the filterhead of FIG. 1.

FIG. 3 is a bottom view of the filter head of FIG. 1, showingparticularly the interior surfaces of the filter head.

FIG. 4 is a top view of the filter cartridge of FIG. 2.

FIG. 5 is a top perspective view of the filter cartridge and filter headof FIGS. 1–4 connected together.

FIG. 6 is a top view of the cartridge and head combination of FIG. 5,with protrusions of the filter cartridge visible through apertures inthe filter head.

FIG. 7 is a side cross-sectional view of the cartridge and headcombination of FIG. 5 and 6, viewed along the lines 7—7 in FIG. 6.

FIG. 8 is an enlarged detail view of a portion of the cross-sectionalFIG. 7.

FIG. 9 is a top view of the filter head of FIGS. 1, 3, 5–8, with thefilter cartridge removed.

FIG. 10 is a side cross-sectional view of the filter of FIGS. 1, 3 5–9,with the filter cartridge removed, viewed along the lines 10—10 in FIG.9.

FIG. 11 is a side cross-sectional view of the filter of FIGS. 1, 3 5–10,with the filter cartridge removed, viewed along the lines 11—11 in FIG.9.

FIG. 12 is a perspective view on an alternative embodiment of a filterholder, a bracket with keyed structure on connection tubes that connectto and fluidly seal to an alternative embodiment of filter cartridge.

FIG. 13 is a bottom, cross-sectional view of the filter holder of FIG.12, viewed along the lines B—B in FIG. 14.

FIG. 14 is an end view of the filter holder of FIGS. 12 and 13.

FIG. 15 is a top view of the filter holder of FIGS. 12–14.

FIG. 16 is a detail view of Section A of FIG. 15, of the filter holderof FIGS. 12–15.

FIG. 17 is a front, cross-sectional view of the filter holder of FIGS.12–16, viewed along the line A—A in FIG. 15.

FIG. 18 is a front view of the filter holder of FIGS. 12–17.

FIG. 19 is a detail view of the inlet and outlet tubes of the filterholder of FIGS. 12–18, viewed as detail B of FIG. 18.

FIG. 20 is a partial side view of one embodiment of a filter cartridge,which is adapted to cooperate with the filter holder of FIGS. 12–19.

FIG. 21 is a partial side view of a filter cartridge of the typecooperating with the filter holder of FIGS. 12–19, but with analternatively-angled key system structure.

FIG. 22 is a partial side view of a filter cartridge of the typecooperating with the filter holder of FIGS. 12–19, but with analternatively-angled key system structure.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Referring to the Figures, there are shown several, but not the onlyembodiments of the invented key system. FIGS. 1–11 illustrate a filtercartridge keyed shoulder embodiment of the invented keyed system. FIGS.12–22 illustrate a tubular connector embodiment of the invented keyedsystem.

Keyed Filter Cartridge Shoulder (FIGS. 1–11)

Referring to FIGS. 1–11, there is shown a preferred, but not the onlyembodiment, of the invented key system for a filter cartridge and afilter holder (hereafter also called a “filter head”). The preferredfilter head 10 and cooperating filter cartridge 20 are illustratedseparately in FIGS. 1 and 2, wherein one may see the “lock” recessstructure included in the head 10 and the “key” protrusion structureincluded on the filter cartridge 20. One may understand from thisDescription that embodiments of the invention also include amirror-image arrangement, wherein “key” protrusions are on the head 10and cooperating “lock” recesses are on the filter cartridge 20. Or, acombination of the two arrangements may be used, wherein one or moresets of “lock” recesses are on the head and cooperating “key”protrusions are on the filter cartridge, plus one or more sets ofprotrusions on the head and cooperating recesses on the filtercartridge.

The preferred embodiment of filter head may be of the general typeillustrated by the systems in U.S. Pat. No. 4,857,189 and Design356,625, and, once the disclosure of the present invention is viewed,one of skill in the art will be able to construct a filter head thatwill be operative and operatively connect with a cooperating filtercartridge. Cartridges conventionally built for such filter head systemsare shown in U.S. Pat. No. 4,857,189 and Design 356,625, for example.

The following discussion describes the preferred embodiment shown in theFigures, plus comments on some variations. One of average skill mayenvision alternative embodiments besides those mentioned that are withinthe scope of the invention.

In the preferred embodiment, the recess structure 22 in the headcomprises an axial portion and a circumferential or “radial lock”portion. The axial portion preferably comprises a plurality of lockrecesses 24 in the inner, lower surface of the head 10, which might becalled the “inside rim” of the filter head near the outer edge 23 of thehead. The lock recesses 24 are separated by partition ridges 28, whichare spaced apart on, and protrude radially inward from, the surfaces ofthe lock recesses 24. In combination with adjacent ridges 26′, partitionridges 28 define the circumferential length of each lock recess 24. Theradial lock portion 40 of the recess structure 22 comprises acircumferentially-extending recess, generally but not necessarilyexactly, transverse to the axis of the head 10 and the filter 10 andlocated “above” ridges 26.

In the preferred molded structure of the interior of the head 10, ridges26 and partition ridges 28 serve as obstacles for any improperly keyedfilter cartridge to be inserted into the filter head 10, and also, oncethe filter cartridge has been rotated on its axis, as obstacles forcartridge removal. Once the filter cartridge is inserted axially pastthe partition ridges 28, by the key protrusions 34 sliding into the headthrough the lock recesses 24, the filter cartridge may then be rotatedso that the key protrusions 34 slide radially into the radial lockportion 40. The filter cartridge is preferably operable only once thefilter cartridge has been inserted axially to the full extent desiredand the filter cartridge has been rotated to lock the cartridge intohead, and preferably only a properly keyed filter cartridge can beinstalled.

The ridges 26 illustrated in FIG. 1 are one example of many embodimentsthat help to define the lower boundary of the radial lock portion 40,and that lock the filter cartridge from axial movement by retaining thekey protrusions 34 in the lock portion 40. The plurality ofclosely-spaced ridges 26 are preferred because they provide a barrier toaxial cartridge movement while minimizing the amount of plastic neededin molding of the head 10. Alternatively, each set of ridges 26 may havethe space between the ridges 26 filled in, that is, replaced with asolid, continuous structure that protrudes, relative to the recessedlock portion 40, inward toward the central axis of the head. Or, ridges26 may be reduced in number or only occupy part of the space below thelock portion 40. In other words, the structure located “below” theradial lock portion 40 near outer edge 23, and serving as an obstacle toaxial movement, may be of various shapes, size, and locations as long asone or more protrusion 33 on the filter cartridge is blocked by saidstructure. At a minimum, therefore, there should be inwardly-protrudingstructure below at least one or more key protrusions 34 when one or moreof the key protrusions 34 in positioned in the lock portion 40. Not allkey protrusions need to be received/engaged in the lock portion, whenthe filter cartridge is “fully rotationally engaged,” which means thepoint at which the filter cartridge is rotated to the fullest extentallowed by a rotation stop in the lock portion. To limit rotation of thefilter cartridge, specifically, to limit radial movement of the keyprotrusions 34 in the radial lock portion 40, a rotation stop surface 41is provided by extensions of ridges 26 or other structure. Thus, radiallock portions of various lengths will have a rotation, even in the caseof closely adjacent sets of lock recesses to prevent rotation of the keyprotrusions past the radial lock portion and into the space above theadjacent set of lock recesses.

In the head 10 of the Figures, the lock recesses 24 are three in numberand are of different circumferential lengths, specifically, threerecesses of long, medium and short length relative to each other. Othernumbers and lengths/sizes may be used, for example, two or fourrecesses, or more, and one long and two short recesses, or two long andtwo short recesses, or a plurality of recesses all of differing lengths.As in a lock and key system for a door latch, many differentcombinations may be devised, and are included in the invention.

While there may be only one set of recess structure and one cooperatingset of protrusion structure, there are preferably more. Preferably,there is are a plurality of sets of recess structure in the filter head,and most preferably, there are two sets of lock recesses 24, each withits connected radial lock portion 40. Preferably, therefore, thecooperating protrusion structure 33 number the same as the recessstructure.

Referring to FIGS. 3 and 4, one may see that the circumferentialdistances of greatest interest may be described as:

-   -   D, which is the circumferential length of the preferred recesses        and the preferred cooperating key protrusions 34;    -   B, which is the distance between the sets of lock recesses or        between the sets of cooperating key protrusions 34, wherein B        includes the radial lock portion 40 of the recess structure,        wherein lock portion 40 may exist in the range of only a small        part of distance B to substantially all of distance B except for        a small radial rotation stop; and    -   T, which is the total distance between the “start” of one set of        lock recesses or cooperating protrusions and the “start” of the        adjacent set.        The absolute lengths of D, T, and B, and the lengths of D, T,        and B relative to each other, may be varied. In the example of        two sets of recess structure (and therefore the two sets of        cooperating protrusion structure) each of the two sets may have        different D lengths.

In FIG. 1, the first set of two recesses is clearly shown, and thesecond set of recesses, located about 180 degrees (distance T) from thefirst set, is located at position 25 on FIG. 1. Thus, these two sets ofrecesses shown in the Figures are generally diametrically opposed, withthe axial portion (lock recesses 24) taking up 70 degrees (distance D)and the radial lock portion 40 taking up about 70 degrees of the 110degrees (distance B) which extends between the two sets of lock recesses24. This results in each part of a recess structure 22 being 180 degreesaway from the corresponding part of the other recess structure, and thetwo recess structures 22 being spaced evenly around the entire 360degrees.

Preferably, the lock portion is as long as the entire length of the keyprotrusions, however, this is not always necessarily the case. Therecess structures 22 may be closer together (distance T) than 180degrees, for example, with two identically-constructed ordifferently-constructed recess structures spaced 90 degrees (distanceT), for example, in which case the lock recesses 24 might take up about70 degrees of that 90 degrees, leaving up to slightly less than 20degrees (20 degrees minus enough distance for a small rotation stop) forthe radial lock portion 40. This would be an example of an embodiment inwhich the radial lock portion is not as circumferentially long as thecircumferential length of the axial portion. In such an embodiment, onlysome of the key protrusions 34 (or part of a key protrusion), wouldslide radially into (“be engaged in”) the lock portion, while some ofthe key protrusions 34 (or part of a key protrusion) would not bereceived (“not engaged”) in the lock portion; this would be sufficient,although not preferred, for locking the cartridge in the head. In thecase of the lock portion being shorter in length than the total lengthof the key protrusions and a key protrusion(s) being unengaged in thelock portion, one or more protrusions or a part of a protrusion, ineffect, would hang over the recesses. In such a case, the unengaged keyprotrusion(s) might still be supported by one or more ridges 28. As longas some of the key protrusion(s) is/are engaged in the lock portion, thefilter cartridge is engaged in the head, until the filter cartridge isrotated in reverse to an unlock point, that is, to a point where allnecessary key protrusions slide can slide down through the recesses.

Another example would be to have, the two recess structures within onlya portion of the circumference of the head 10, for example, within 180degrees (for two recess structures where T=90 degree) or 270 degrees(for two recess structures where T=135 degrees).

Preferably, the recesses in each set of recesses are all containedwithin 90 degrees or less (distance D) or, more preferably, within 70degrees or less (distance D). Especially preferred embodiments haverecesses (and likewise cooperating protrusions) from a maximum of 70degrees down to a minimum of 30 degrees on the circumference of theinner rim of the filter head. Less than 30 is also possible, but is lesspreferred. In FIG. 1, the first set of recesses is within about 70degrees (“D” in FIGS. 3 and 4).

Distance B may be within a wide range of lengths. For example,preferably, but not necessarily, B may be up to about 150 degrees (Bequals 150 degrees when, for example, D is 30 degrees and T is 180degrees) and down to about 30 degrees (B equals 30 degrees when, forexample, D is 70 degrees and T is 100 degrees; or B equals 30 degreeswhen, for example, D is 30 degrees and T is 60 degrees). Other Bdistances may be outside the range of 30–150 degrees, particularly whenB is very large (greater than 150 degrees) because D is very small (lessthan 30 degrees) or when B is very small (less than 30 degrees) becausethe two sets of recesses are very close together. In the case where B isvery small, one would expect many of such embodiments to have radiallock portions only a fraction of the length of D, that is, only part ofthe key protrusions would fit into the radial lock portion beforehitting a rotation stop in the radial lock portion.

Also shown in FIG. 4 are lengths 134, 134′, 134″ of the key protrusions(which preferably equate to very slightly less than the lengths of thematching lock recesses 24), and the lengths of spaces 128, 128′ betweenthe protrusions (which preferably equate to very slightly more than thelengths of the matching ridges 28. Preferably, but not necessarily, thelengths 134, 134′, 134″ (which are not necessarily equal to each other)are much greater than the lengths of the spaces 128, 128′ (which are notnecessarily equal to each other). For example, preferably the lengths ofsaid protrusion are at least twice that of said spaces, and, morepreferably three times or more.

FIG. 2 illustrates a filter cartridge 20 that is keyed to cooperate withthe head 10 of FIG. 1. The central neck 29 of the filter cartridgecontains the connections/seals for fluid communication between thecartridge and the head. Radially spaced from the neck 29 is shoulder 32.On shoulder 32 are two sets 33 of key protrusions 34, generallydiametrically opposed to match the locations of the two sets of lockrecesses in the filter head. Each set of key protrusions includes thesame number, size, and arrangement of key protrusions 34 as the filterhead has lock recesses, so that the “key” of the filter cartridge fitsinto the “lock” of the filter head, in effect. The preferred keyprotrusions curve on the radius of the shoulder of the cartridge andhave a curved outer surface from top to bottom. To match the recesses,each set of protrusions in the embodiment of FIG. 2 include three“end-to-end” protrusions, sized large, medium, and small, in sizes equalto the recesses in FIG. 1.

In use, when the filter cartridge 20 is inserted into the head 10, thekey protrusions 34 must be matched up with the lock recesses 24 so thatthe filter cartridge can be moved axially into the filter head. Theprotrusions 34 slide into their corresponding lock recesses 24 (whichare the first portion of the recess system) and the inner rim of thehead extends down over the top of the filter cartridge. Then, the filtercartridge is rotated on its axis relative to the head to lock thecartridge into the head. This is made possible by the second portion ofthe recess system of the filter head, the radial lock portion 40, whichextends continuously above the ridges 26 for preferably, but notnecessarily, a distance equal to or slightly greater than the totallength of one set of protrusions. When the cartridge is inserted androtated, the protrusions 34 slide circumferentially into the radial lockportion 40 of the recess system until being fully rotationally engaged(rotationally limited by the stop at the end of the lock portion) andare “locked” above the ridges 26 by virtue that they cannot be pulledaxially downward past the ridges 26. When the filter cartridge is fullyinserted and locked into the head, as shown in FIG. 5 and 6, one may seethe protrusions 34 through the apertures 42 in the filter head wall. Toremove the filter cartridge, the cartridge is rotated on its axis in theopposite direction to move the protrusions 34 from above the ridges 26to again align with lock recesses 24, so that the protrusions may slideaxially down and out of the head through the recesses. Frictional meansor biasing means, or other locking means may be used to bias the filtercartridge from sliding in reverse out of the head until the userpurposely removes the filter cartridge.

With the invented key system for filter cartridge and head, it iseconomical and convenient to mold sets of cartridges and heads withmatching key system structure, and to mold many different sets withdifferent key system structure. For example, for one application, a keysystem structure may include four lock recesses and four key protrusionsin each of two sets on the cartridge and on the head, and the recessesand protrusions may be, for example, two short alternating with twolong. For another application, a key system structure may include threerecesses and three protrusions, all of which are long. Cartridges withthe three-recess and protrusion key system would not fit into heads withthe four-recess and protrusion key system, so there would be no chanceof mixing up the cartridges.

Keyed Fluid Connector (FIGS. 12–22):

An alternative embodiment of the invented keyed system provides the keysystem structure on surfaces of the filter cartridge and the holder thatwork to provide a fluid connection/seal in addition to physicalconnection. FIGS. 12–22 illustrate such a tubular connector embodiment,comprising a bracket 210 that is a fluid-conducting holder for holdingand sealing to a filter cartridge 211. The bracket 210 and cartridge 211include tabs and slots on the tubular connectors that create a physicalconnection and fluid communication between the bracket and cartridge.

In FIG. 12 is shown the bracket 210 that serves several function:mounting means for securing the bracket to a wall of other surface,fluid receiving means, inlet tube for conveying liquid to the filterconnected (not shown in FIGS. 12–19, but shown separately in FIG.20–22); outlet tube for conveying liquid from the filter; and fluiddispensing means for sending the filtered/treated liquid downstream toanother filter, process, storage, or use. Specifically, plate 212 may beattached to a wall or other surface for supporting several brackets invarious flow configurations. Inlet 214 and outlet 216 are at oppositeends of a conduit device 218, and may be used so that inlet 214 receivesfluid from an upstream pipe or other conduit and that outlet 216delivers filtered fluid (that has exited the filter cartridge) to itsdownstream destination. The conduit device 218 directs flow into theinlet tube 220 so that the fluid may flow into the filter cartridge, andthen receives flow from the cartridge into the outlet tube 222 so thatit may flow out through outlet 216. Male tubes 220 and 222 have“standouts” or tabs 225,225′ on their outer cylindrical surfaces.

As best seen in FIGS. 18 and 19, tube 220 and tube 222 have tabs 225,225′ protruding about 30 degrees offset from each other (tab 225 of tube220 out to the left in FIG. 19 and tab 225′ of tube 222 down about 30degrees from the tab 225 of tube 220). The cooperating filter cartridge228 shown schematically in FIG. 20 has female inlet and outlet tubes 230and 232 (which may also be called an inlet port and outlet port), andone may notice that tubes 230 and 232 have matched or “mating” internalslots 227, 227′ to receive the tabs 225, 225′. Alternatively, of course,filter cartridges might be made with male tubes and tabs and cooperatingholders may be made with female tubes and slots.

One may see that, by varying the radial location of the tabs and slots,one could arrive at many “keys” and “locks” for the cartridge-holdersets. For example a holder could have an inlet tube with a tab at 60degrees from a reference point and the outlet tube could have a tab at120 degrees relative to that reference point, as long as the propercartridge for that holder is made with the same offset and the sameabsolute location of slots. FIGS. 12–22 illustrate only one set of themany possible combinations of possible tab radial locations, which areextremely numerous because the radial location of each of the tubes maybe varied in each set, and may be varied independently. FIGS. 21 and 22illustrate two of the many other possible key system structures. Forexample, in the top end of elongated filter cartridge 228′ of FIG. 21,the female inlet tube (port) 230′ is keyed at about 110 degrees, and thefemale outlet tube (port) 232′ is keyed at about 290 degrees. In the topend of elongated filter cartridge 228″ of FIG. 22, the inlet tube 230″is keyed at about 195 degrees and the outlet tube 232″ is keyed at about170 degrees.

The bracket 10 in FIGS. 12–19 typically is installed in a process withthe plate 212 vertically attached to a vertical wall. Thus, tubes 220and 222 extend out horizontally, and the filter cartridge is pushed ontothe tubes 220, 222 so that the tubes 220 and 222 support and connectwith the filter cartridge. Associated with the tubes 220, 222, 230, 232are o-rings or other sealing structure to provide liquid-tightcommunication between the bracket and the cartridge. Although it is notshown, one may see from FIGS. 12–19 that liquid-tight seals are madebetween piping or other conduit and the inlet 214 and outlet 216.Additionally, a fastening device may be added to further secure thecartridge in sealed relationship with the tubes 220, 222.

Although this invention has been described above with reference toparticular means, materials and embodiments, it is to be understood thatthe invention is not limited to these disclosed particulars, but extendsinstead to all equivalents within the scope of the following claims.

1. A keyed system for a filtration unit, the keyed system comprising: afilter and a cooperating holder, wherein the filter has a filter surfacewith a perimeter having a key protrusion and the cooperating filterholder has a holder surface with a perimeter with a cooperating lockrecess for receiving the key protrusion of the filter, so that thefilter is insertable into the holder because the key protrusion slidesinto the lock recess; wherein the key protrusion comprises a pluralityof protrusions all contained within less than a 70 degree arc on acurved surface of the top end of the filter; and wherein the location ofthe key protrusion and the lock recess on said perimeters is selectivelylocateable to different circumferential locations on said perimeters sosaid keyed system is adapted to prevent said filter from being installedin any but its cooperating holder; wherein the filter is an elongatedfilter with an longitudinal axis and a radius, and wherein said keyprotrusion is on an upper shoulder of a top end of the filter, and thelock recess is on an inner surface of a cavity of a holder, wherein thecavity receives the filter top end; and wherein the key protrusioncomprises three protrusions contained within said less than 70 degreearc on the upper shoulder of the top end of the filter.
 2. A keyedsystem for a filtration unit, the keyed system comprising: a filter anda cooperating holder, wherein the filter has a filter surface with aperimeter having a key protrusion and the cooperating filter holder hasa holder surface with a perimeter with a cooperating lock recess forreceiving the key protrusion of the filter, so that the filter isinsertable into the holder because the key protrusion slides into thelock recess; wherein the key protrusion comprises a plurality ofprotrusions all contained within less than a 70 degree arc on a curvedsurface of the top end of the filter; and wherein the location of thekey protrusion and the lock recess on said perimeters is selectivelylocateable to different circumferential locations on said perimeters sosaid keyed system is adapted to prevent said filter from being installedin any but its cooperating holder; wherein the filter is an elongatedfilter with an longitudinal axis and a radius, and wherein said keyprotrusion is on an upper shoulder of a top end of the filter, and thelock recess is on an inner surface of a cavity of a holder, wherein thecavity receives the filter top end; and further comprising a second keyprotrusion comprising a plurality of protrusions contained within lessthan a 70 degree arc on the upper shoulder of the top end of the filterand generally 180 degrees apart from said key protrusion.
 3. The keyedsystem of claim 1, wherein the lock recess comprises a plurality ofrecesses within a 70 degree arc on the inner surface of the cavity. 4.The keyed system of claim 2, wherein the lock recess comprises threerecesses contained entirely within less than a 70 degree arc on theinner surface of the cavity.
 5. The keyed system of claim 4, wherein therecesses are axial slots in the cavity surface parallel to thelongitudinal axis of the filter, and the lock recess further comprises acircumferentially-extending lock recess, and wherein the filter isadapted to rotate after insertion into the holder so that the keyprotrusion slides into the lock recess of the holder to lock the filterin the holder.
 6. The keyed system of claim 4, wherein the recesses areaxial slots in the cavity surface parallel to the longitudinal axis ofthe filter, and the lock recess further comprises acircumferentially-extending lock recess, and wherein the filter isadapted to rotate after insertion into the holder so that the keyprotrusion slides into the lock recess of the holder to lock the filterin the holder.
 7. A keyed system for a filtration unit, the keyed systemcomprising: a filter and a cooperating holder, wherein the filter holderhas a tubular outer surface having a radially-outward-extending keyprotrusion and the cooperating filter has a tubular inner surface havinga radially-inwardly-extending lock recess adapted to receive the keyprotrusion of the cooperating holder, so that the filter is insertableinto the holder because the key protrusion of the holder slides into thelock recess of the filter; wherein the locations of the key protrusionand the lock recess on said tubular outer and inner surfaces areselectively locateable to different circumferential locations on saidtubular outer and inner surfaces to prevent said filter from beinginstalled in any but its cooperating filter holder; wherein said tubularouter surface is the outer surface of a male fluid tube that connectswith the filter, and wherein the tubular inner surface is the innersurface of a female fluid tube that connects to and seals with the malefluid tube; and wherein the holder has two male fluid tubes, wherein oneof the two male fluid tubes is a liquid-inlet tube for conveying liquidto the filter, and the other of the two male connector tubes is aliquid-outlet tube for conveying liquid away from the filter, andwherein both of the two male connector tubes have a lock protrusion ontheir outer surfaces.
 8. A keyed system as in claim 7, wherein each ofsaid male fluid tubes has a single key protrusion extending out itsouter surface.
 9. A keyed system as in claim 7, wherein the filter hastwo female fluid tubes that connect with and seal to said two male fluidtubes, and wherein both of the two female fluid tubes have a key recesson their inner surfaces.
 10. A keyed system as in claim 9, wherein eachof said female fluid tubes has a single lock recess.
 11. A filtrationassembly including the subassembly of a keyed filter and the subassemblyof a cooperating holder, wherein the cooperating holder has a holdersurface with a circumferential perimeter having a first cooperatingrecess structure having a plurality of axial portions separated byradially-protruding ridges, and the cooperating recess structure furtherhaving one circumferentially-extending lock portion having an open endnear, and in mechanical communication with, said axial portions andhaving a closed opposite end; the filter subassembly comprising: afilter surface with a perimeter having a first set of a plurality of keyprotrusions, wherein said key protrusions slide through the axialportions during axial insertion of the filter into the holder and, uponangular rotation of the filter in the holder, said first set of aplurality of key protrusions are received in the onecircumferentially-extending lock portion.
 12. The filter subassembly ofclaim 11, wherein the filter is an elongated filter with an longitudinalaxis and a radius, and wherein said first set of key protrusions are onan upper shoulder of a top end of the filter, and the recess structureis on an inner surface of a cavity of a holder, wherein the cavityreceives the filter top end.
 13. The filter subassembly of claim 12,wherein said first set of key protrusions are all within a 90 degree arcon the upper shoulder of the top end of the filter.
 14. The filtersubassembly of claim 12, wherein said first set of key protrusions areall within less than a 70 degree arc on the upper shoulder of the topend of the filter.
 15. A keyed system as in claim 8, wherein the singlekey protrusion extending out from said tubular outer surface of each ofsaid male fluid tubes consists of an elongated axial tab.
 16. A keyedsystem as in claim 9, wherein the single lock recess of each of saidfemale fluid tubes consists of an elongated axial channel.